EP4321772A1 - Rückfahrbarer aktuator für exoskelett - Google Patents

Rückfahrbarer aktuator für exoskelett Download PDF

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Publication number
EP4321772A1
EP4321772A1 EP22382778.3A EP22382778A EP4321772A1 EP 4321772 A1 EP4321772 A1 EP 4321772A1 EP 22382778 A EP22382778 A EP 22382778A EP 4321772 A1 EP4321772 A1 EP 4321772A1
Authority
EP
European Patent Office
Prior art keywords
actuator
pulley
motor
torque
output
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22382778.3A
Other languages
English (en)
French (fr)
Inventor
Pau MOREY OLIVÉ
Alex GARCIA FARRENY
Guim PEDRERO TOBELLA
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Able Human Motion SL
Original Assignee
Able Human Motion SL
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Able Human Motion SL filed Critical Able Human Motion SL
Priority to EP22382778.3A priority Critical patent/EP4321772A1/de
Priority to PCT/IB2023/055080 priority patent/WO2024033712A1/en
Publication of EP4321772A1 publication Critical patent/EP4321772A1/de
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H7/00—Gearings for conveying rotary motion by endless flexible members
    • F16H7/02—Gearings for conveying rotary motion by endless flexible members with belts; with V-belts
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H3/00—Appliances for aiding patients or disabled persons to walk about
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/0006—Exoskeletons, i.e. resembling a human figure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/10—Programme-controlled manipulators characterised by positioning means for manipulator elements
    • B25J9/104—Programme-controlled manipulators characterised by positioning means for manipulator elements with cables, chains or ribbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H7/00—Gearings for conveying rotary motion by endless flexible members
    • F16H7/02—Gearings for conveying rotary motion by endless flexible members with belts; with V-belts
    • F16H7/023—Gearings for conveying rotary motion by endless flexible members with belts; with V-belts with belts having a toothed contact surface or regularly spaced bosses or hollows for slipless or nearly slipless meshing with complementary profiled contact surface of a pulley
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H9/00—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by endless flexible members
    • F16H9/02—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by endless flexible members without members having orbital motion
    • F16H9/24—Gearings for conveying rotary motion with variable gear ratio, or for reversing rotary motion, by endless flexible members without members having orbital motion using chains or toothed belts, belts in the form of links; Chains or belts specially adapted to such gearing
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H2201/00—Characteristics of apparatus not provided for in the preceding codes
    • A61H2201/12—Driving means
    • A61H2201/1207—Driving means with electric or magnetic drive
    • A61H2201/1215—Rotary drive
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H2201/00—Characteristics of apparatus not provided for in the preceding codes
    • A61H2201/14—Special force transmission means, i.e. between the driving means and the interface with the user
    • A61H2201/1418—Cam
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H2201/00—Characteristics of apparatus not provided for in the preceding codes
    • A61H2201/14—Special force transmission means, i.e. between the driving means and the interface with the user
    • A61H2201/1454—Special bearing arrangements
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H2201/00—Characteristics of apparatus not provided for in the preceding codes
    • A61H2201/14—Special force transmission means, i.e. between the driving means and the interface with the user
    • A61H2201/1463—Special speed variation means, i.e. speed reducer
    • A61H2201/1472—Planetary gearing

Definitions

  • the present invention in some embodiments thereof, relates to an actuator and, more particularly, but not exclusively, to a backdrivable actuator for an exoskeleton.
  • gearboxes achieve high gear reductions at high efficiencies and in compact sizes through the use of the Wolfrom gearbox topology, combined with performance-enhancing modifications such as a carrierless design (Gear Bearing Drive) and profile shift modification (Bilateral Drive).
  • a carrierless design Gear Bearing Drive
  • Bilateral Drive profile shift modification
  • quasi-direct drive has emerged as a new actuation paradigm. It combines high torque-motors with low-reduction gearboxes, resulting in energy-efficient actuators with high backdrivability.
  • these gearboxes are single-stage (gear ratio below 10) since efficiency is mostly related to the number of stages.
  • a publication by Alejandro F. Azocar et al, "Design and clinical implementation of an open-source bionic leg" discloses a design and clinical implementation of an integrated robotic knee-ankle prosthesis that facilitates the real-world testing of its biomechanics and control strategies.
  • the bionic leg is open source, it includes software for low-level control and for communication with control systems, and its hardware design is customizable, enabling a reduction in its mass and cost, improvement in its ease of use and independent operation of the knee and ankle joints.
  • a publication by Shuangyue Yu et al, "Quasi-Direct Drive Actuation for a Lightweight Hip Exoskeleton with High Backdrivability and High Bandwidth” discloses a design and human-robot interaction modeling of a portable hip exoskeleton based on their custom quasi-direct drive (QDD) actuation (i.e., a high torque density motor with low ratio gear). They present a model-based performance benchmark comparison of representative actuators in terms of torque capability, control bandwidth, backdrivability, and force tracking accuracy. They created a lightweight bilateral hip exoskeleton to reduce joint loadings during normal activities, including walking and squatting.
  • QDD quasi-direct drive
  • Additional background art includes U.S. Patent No. US10702441B2 disclosing an exoskeleton that includes first and second supports coupled to an exoskeleton wearer, a joint connecting the first support to the second support and an actuator.
  • the actuator includes a ball screw, a ball nut assembly coupled to the ball screw and first and second tensile members.
  • the ball nut assembly has first and second cord reactors. The first tensile member is routed through the first cord reactor, and the second tensile member is routed through the second cord reactor. Movement of the ball nut assembly along the ball screw in a first direction causes the second support to move relative to the first support in a first rotational direction about the joint. Movement of the ball nut assembly along the ball screw in a second direction causes the second support to move relative to the first support in a second rotational direction about the joint.
  • U.S. Patent Application Publication No. US20210290470A1 disclosing a joint actuator assembly for a legged mobility device which includes a motor that drives a joint connector for driving a joint of the mobility device, and a three-stage transmission of speed reduction to result in a high torque, low speed output.
  • the first stage may include a small sprocket mechanically connected to the output shaft of the motor, and a large sprocket driven by a cable chain to provide the first speed reduction.
  • the second stage may include a small central helical gear mechanically connected to the first stage output, and two opposing larger first and second outer helical gears that mesh with the central gear to provide the second speed reduction.
  • the third stage may include a cable reel assembly including an output reel and a cable element that interconnects the output of the second stage and the output reel to provide the third speed reduction.
  • U.S. Patent Application Publication No. US20210338515A1 disclosing a joint actuator assembly which includes a motor, a rotating driving member driven by the motor for driving a driven component, and a transmission assembly located between the motor and the rotating driving member that provides speed reduction from the motor to the rotating driving member.
  • the rotating driving member comprises a magnetic coupling including a plurality of magnetic elements that are configured to magnetically couple with an opposing magnetic coupling of the driven component.
  • the actuator and driven component may be combined into a mobility device including a magnetic coupling system having a first magnetic coupling on the actuator that magnetically couples to a second magnetic coupling on the driven component.
  • the magnetic coupling system includes plurality of magnetic elements located as part of one or both of the first and second magnetic couplings. The first and second couplings have opposing mating surfaces that join together in a coupled position.
  • WO2013140390A1 disclosing a motorized exoskeleton device for facilitating locomotion for a user, the device including, a torso base for affixing to the torso of the user, a pair of limb members configured to be coupled to a lower extremity of the user.
  • Each limb member includes, a first support segment and a second support segment, where the first support segment is superior to the second support segment two motorized joints, one of the motorized joints connecting the first support segment to the second support segment and another motorized joint connecting the first support segment to the torso base and two motors configured to move the motorized joints, wherein the motors are coupled to the superior support segment.
  • U.S. Patent No. US9566705B2 disclosing an exoskeleton for applying force to at least one lower limb of a user that includes a control system with a sensor interface for sensor signals; a power interface for transmitting control signals to the powered joint; a processor coupled to the sensor and the power interfaces; and a computer-readable medium storing a computer program executable on the processor with code sections for: estimating a configuration of a body of the user with respect to a gravity vector based on the sensor signals; computing a control torque for the powered joint that compensates gravitational dynamics of the user based on the configuration; calculating a gravitational energy gradient for the powered joint; attenuating the control torque based on the gravitational energy gradient; computing a final control torque based on the attenuated control torque, and configuring the control signals based on the attenuated control torque.
  • Japanese Patent No. JP6765989B2 disclosing, in a long lower extremity orthosis, a control device that: calculates a thigh phase angle on the basis of an angle related signal input from thigh attitude detection means at one sampling point; applies the thigh phase angle at the one sampling point to assist force control data pre-stored in the control device and representing a relation between the thigh phase angle and the assist force to be applied to a lower thigh-side orthosis; calculates the assist force to be applied to the lower thigh-side orthosis at the one sampling point; and performs operation control of the actuator such that the assist force is output.
  • Korean Patent No. KR101724884B1 disclosing a step of deriving a hip joint angle and an angular velocity of a knee joint and a swing leg of a robot supporting leg, a comparison step of comparing values of angles and angular velocities of the support legs and the swing legs with preset reference values of angles and angular velocities, calculating an assist torque value using an angle or an angular velocity derived from the support leg when an angle and an angular velocity of the derived support leg and swing leg satisfy a predetermined reference condition, and a method and system for stair walking control of a wearable robot including application steps applied to a knee joint.
  • U.S. Patent No. US10213357B2 disclosing an ambulatory exoskeleton that can be selectively operated in at least two different modes, with one mode constituting an unworn propulsion mode, used when the exoskeleton is not worn by a user, and another mode constituting a default or worn propulsion mode, used when the exoskeleton is worn by a user.
  • a physical therapist, or other operator wishing to move an unworn exoskeleton, can balance the unworn exoskeleton, while simultaneously utilizing a control system and actuators of the exoskeleton to propel the unworn exoskeleton.
  • the exoskeleton walks by taking steps forward, as commanded by the operator using any of a plurality of input arrangements, while the operator balances and steers the exoskeleton by physically guiding the exoskeleton using a handle or other interaction surface of the exoskeleton.
  • U.S. Patent Application Publication No. US20210085552A1 disclosing a gait motion assisting apparatus including an actuator unit controlling driver so that assisting force calculated by applying gait motion timing based on detected thigh phase angle to output pattern saved data is imparted to lower leg, and a terminal device capable of wireless-communicating with control device of the actuator unit.
  • the terminal device can receive assisting force setting value including assisting force imparting period during gait cycle and create, based on the assisting force setting value, output pattern setting data indicating a relationship between the gait motion timing and a size of assisting force to be imparted to the lower leg.
  • the control device is configured to overwrite-save the output pattern setting data received from the terminal device as the output pattern saved data.
  • U.S. Patent Application Publication No. US20210275382A1 disclosing a joint actuator assembly which includes a motor, a rotating driving member driven by the motor for driving a driven component, and a transmission assembly located between the motor and the rotating driving member that provides speed reduction from the motor to the rotating driving member.
  • the rotating driving member includes a magnetic/electrical coupling comprising a magnetic coupling component configured to magnetically couple with an opposing magnetic coupling of the driven component, and an electrical element configured to provide an electrical connection to an opposing electrical element of the driven component.
  • the actuator and driven component may be combined into a mobility device including a magnetic/electrical coupling system comprising a first magnetic/electrical coupling on the actuator assembly that magnetically and electrically couples to a second magnetic/electrical coupling on the driven component.
  • the magnetic coupling system includes a plurality of magnetic elements located on the first and/or second magnetic/electrical couplings and opposing electrical elements for electrical connection when the actuator assembly and the driven component are joined together.
  • U.S. Patent Application Publication No. US20210039248A1 disclosing a motion control system, which includes an actuator having an actuation member, the actuation member having a proximal end attached to the actuator on a first side of a joint and a distal end attached to an anchor element attachment point on a second side of the joint.
  • a first sensor is configured to output signals defining a gait cycle and a second sensor is configured to output signals representing a tensile force in the at least one actuation member.
  • a controller receives the output signals from the first and second sensors and, responsive thereto, automatically actuates the actuator, during a first portion of the gait cycle, to apply a force greater than a predetermined threshold tensile force to the anchor element attachment point via the actuation member to generate a beneficial moment about the joint and to automatically actuate the actuator, during at least a second portion of the gait cycle, to reduce a tensile force at the anchor element attachment point to a level at or below the predetermined threshold tensile force to avoid generating a detrimental moment about the joint.
  • Example 1 An actuator, comprising:
  • Example 2 The actuator according to example 1, wherein said at least one motor, said at least one input pulley and said at least one output pulley are coaxially located and in the same plane within said actuator.
  • Example 3 The actuator according to example 1 or example 2, wherein said at least one reduction assembly performs a reduction from about 1:10 to about 1:50.
  • Example 4 The actuator according to any one of examples 1-3, wherein said at least one reduction assembly comprises:
  • Example 5 The actuator according to example 3, wherein said at least one additional pulley is outside said at least one motor, said at least one input pulley and said at least one output pulley but on a same plane as said at least one motor, said at least one input pulley and said at least one output pulley.
  • Example 6 The actuator according to any one of examples 1-5, wherein said at least one input pulley and said at least one additional pulley provide a reduction of from about 1:3 to about 1:6.
  • Example 7 The actuator according to any one of examples 1-6, wherein said at least one additional pulley and said at least one output pulley provide a reduction of from about 1:2 to about 1:6.
  • Example 8 The actuator according to any one of examples 1-7, wherein said at least one motor is a high torque motor.
  • Example 9 The actuator according to any one of examples 1-8, wherein said actuator is characterized by having a mid-low backdriving torque from about 0.5 Nm to about 2.5 Nm and is configured to provide high nominal torque from about 10 Nm to about 100 Nm.
  • Example 10 The actuator according to any one of examples 1-9, wherein said actuator is configured to allow said motor to backdrive.
  • Example 11 The actuator according to any one of examples 1-10, wherein said motor is configured to allow said actuator to backdrive.
  • Example 12 The actuator according to any one of examples 1-11, wherein said motor is a backdrivable motor.
  • Example 13 The actuator according to any one of examples 1-12, wherein:
  • Example 14 The actuator according to any one of examples 1-13, further comprising at least one energy source configured for providing energy to said actuator.
  • Example 15 The actuator according to any one of examples 1-14, further comprising at least one encoder configured for providing real-time information about a position of said at least one input pulley of input and said at least one output pulley.
  • Example 16 The actuator according to any one of examples 1-15, further comprising at least one brake configured for locking said actuator in case of emergency.
  • Example 17 The actuator according to any one of examples 1-16, wherein said at least one motor and said at least one two-stage reduction assembly are configured to provide said actuator with capabilities for delivering a maximum torque/weight ratio from about 40 Nm/Kg to about 100 Nm/Kg.
  • Example 18 An actuator, comprising:
  • Example 19 The actuator according to example 18, wherein said at least one motor, said at least one input pulley and said at least one output pulley are inside each other within said actuator.
  • Example 20 The actuator according to example 18, wherein said at least one motor, said at least one input pulley and said at least one output pulley are coaxially located and in the same plane within said actuator.
  • Example 21 The actuator according to any one of examples 18-20, wherein said at least one reduction assembly comprises:
  • Example 22 The actuator according to example 21, wherein said at least one additional pulley is outside said at least one motor, said at least one input pulley and said at least one output pulley but on a same plane as said at least one motor, said at least one input pulley and said at least one output pulley.
  • Example 23 The actuator according to any one of examples 18-22, wherein said at least one input pulley and said at least one additional pulley provide a reduction of from about 1:3 to about 1:6.
  • Example 24 The actuator according to any one of examples 18-23, wherein said at least one additional pulley and said at least one output pulley provide a reduction of from about 1:2 to about 1:6.
  • Example 25 The actuator according to any one of examples 18-24, wherein:
  • Example 26 The actuator according to any one of examples 18-25, further comprising at least one energy source configured for providing energy to said actuator.
  • Example 27 The actuator according to any one of examples 18-26, further comprising at least one encoder configured for providing real-time information about a position of said at least one input pulley of input and said at least one output pulley.
  • Example 28 The actuator according to any one of examples 18-27, further comprising at least one brake configured for locking said actuator in case of emergency.
  • Example 29 An actuator, comprising:
  • Example 30 The actuator according to example 29, wherein said at least one motor is a high torque motor.
  • Example 31 The actuator according to example 28 or example 29, wherein said at least one motor and said at least one two-stage reduction assembly are configured to provide said actuator with said capabilities without compromising backdrivability capabilities of said actuator.
  • Example 32 The actuator according to any one of examples 28-31, wherein said at least one motor, said at least one input pulley and said at least one output pulley are inside each other within said actuator.
  • Example 33 The actuator according to any one of examples 28-31, wherein said at least one motor, said at least one input pulley and said at least one output pulley are coaxially located and in the same plane within said actuator.
  • Example 34 The actuator according to any one of examples 28-33, wherein said at least one reduction assembly performs a reduction from about 1:10 to about 1:50.
  • Example 35 The actuator according to any one of examples 28-34, wherein said at least one reduction assembly comprises:
  • Example 36 The actuator according to example 35, wherein said at least one additional pulley is outside said at least one motor, said at least one input pulley and said at least one output pulley but on a same plane as said at least one motor, said at least one input pulley and said at least one output pulley.
  • Example 38 The actuator according to any one of examples 28-37, wherein said at least one input pulley and said at least one additional pulley provide a reduction of from about 1:3 to about 1:6.
  • Example 39 The actuator according to any one of examples 28-38, wherein said at least one additional pulley and said at least one output pulley provide a reduction of from about 1:2 to about 1:6.
  • Example 40 The actuator according to any one of examples 28-39, wherein said motor is characterized by having a mid-low backdriving torque from about 0.5 Nm to about 2.5 Nm and is configured to provide high nominal torque from about 10 Nm to about 100 Nm.
  • Example 41 The actuator according to any one of examples 28-40, wherein:
  • Example 42 The actuator according to any one of examples 28-41, further comprising at least one energy source configured for providing energy to said actuator.
  • Example 43 The actuator according to any one of examples 28-42, further comprising at least one encoder configured for providing real-time information about a position of said at least one input pulley of input and said at least one output pulley.
  • Example 44 The actuator according to any one of examples 28-43, further comprising at least one brake configured for locking said actuator in case of emergency.
  • Example 45 An actuator, comprising:
  • Example 46 The actuator according to example 45, wherein said at least one motor, said at least one input pulley and said at least one output pulley are coaxially located and in the same plane within said actuator.
  • Example 47 The actuator according to example 45 or example 46, wherein said at least one motor and said at least one two-stage reduction assembly are configured to provide said actuator with said capabilities without compromising backdrivability capabilities of said backdrivable motor.
  • Example 48 The actuator according to any one of examples 45-47, wherein said at least one reduction assembly comprises:
  • Example 49 The actuator according to example 48, wherein said at least one additional pulley is outside said at least one motor, said at least one input pulley and said at least one output pulley but on a same plane as said at least one motor, said at least one input pulley and said at least one output pulley.
  • Example 50 The actuator according to any one of examples 45-49, wherein said at least one input pulley and said at least one additional pulley provide a reduction of from about 1:3 to about 1:6.
  • Example 51 The actuator according to any one of examples 45-50, wherein said at least one additional pulley and said at least one output pulley provide a reduction of from about 1:2 to about 1:6.
  • Example 52 The actuator according to any one of examples 45-51, wherein:
  • Example 53 The actuator according to any one of examples 45-52, further comprising at least one energy source configured for providing energy to said actuator.
  • Example 54 The actuator according to any one of examples 45-53, further comprising at least one encoder configured for providing real-time information about a position of said at least one input pulley of input and said at least one output pulley.
  • Example 55 The actuator according to any one of examples 45-54, further comprising at least one brake configured for locking said actuator in case of emergency.
  • Example 56 An exoskeleton, comprising:
  • Example 57 The exoskeleton according to example 56, wherein said at least one actuated applied part is attached to one or more segments selected from the group consisting of thigh, shank, foot, trunk, forearm, upper arm and hand.
  • Example 58 The exoskeleton according to example 56 or example 57, further comprising at least one circuit configured for controlling said motor of said at least one actuator.
  • Example 59 The exoskeleton according to any one of examples 56-58, wherein said at least one output unit provides an output range of motion (ROM) of from about 45° to about 180° to said at least one actuated applied part.
  • ROM output range of motion
  • Example 60 The exoskeleton according to any one of examples 56-59, wherein said at least one actuator is located inside a dedicated unit in said exoskeleton, and wherein said dedicated unit is located on one or more segments selected from the group consisting of thigh, shank, foot, trunk, forearm, upper arm and hand.
  • Example 61 The exoskeleton according to any one of examples 56-60, wherein said at least one output unit is located outside of said dedicated unit.
  • Example 61 The exoskeleton according to any one of examples 56-60, wherein said at least one output unit is located at the location of said at least one actuated applied part.
  • Example 62 The exoskeleton according to any one of examples 56-61, further comprising at least one energy source configured for providing energy to said exoskeleton.
  • the present invention in some embodiments thereof, relates to an actuator and, more particularly, but not exclusively, to a backdrivable actuator for an exoskeleton.
  • An aspect of some embodiments of the invention relates to a backdrivable actuator comprising a coaxial input-out layout and a combination of a high torque-motor with an efficient low ratio transmission system.
  • the actuator comprises a 2-stage timing belt transmission embedded in a compact package.
  • a potential advantage of this configuration is that the backdrivability, the torque and the velocity are not affected by this configuration.
  • the actuator comprises a tensioning mechanism comprising a compact footprint, which potentially allows tensioning each belt independently and precisely.
  • a potential advantage of the actuator of the invention is that by using a backdrivable actuator as disclosed herein, the system is lighter, more compact, cheaper, more efficient and has higher bandwidth compared to the traditional high reduction ratio gearboxes. In some embodiments, this is also achieved by avoiding sub-optimal dynamics of high reduction gearboxes and by potentially avoiding possible delays caused by the addition of sensors within the system. In some embodiments, the actuator of the invention potentially allows for a better human-machine interaction and potentially allows people with incomplete injuries to use the exoskeleton.
  • the exoskeleton comprises two silent, high-efficient and backdrivable actuators with about 60 Nm max torque and about 36 Nm nominal torque. In some embodiments, the exoskeleton comprises a knee safety brake of about 36 Nm. In some embodiments, the exoskeleton comprises an improved length regulation mechanism. In some embodiments, the exoskeleton comprises an improved cable routing. In some embodiments, the exoskeleton comprises a closed system, which avoids finger trapping.
  • An aspect of some embodiments of the invention relates to a backdrivable actuator for a lower-limb exoskeleton.
  • the manufacturing costs of the actuator are cheaper when compared with known actuators that use high reduction ratios.
  • the actuator is lighter when compared to known actuators.
  • the actuator is configured to provide a maximum torque from about 40 Nm/Kg to about 100 Nm/Kg.
  • a potential advantage of the actuator is that the configuration allows to provide a high torque in a more efficient manner, when compared to other actuators.
  • known planetary gearboxes comprising a T-Motor AK10-9 are configured to provide a torque of about 50 Nm/Kg
  • known Harmonic gears comprising a FLA-20A-100CD are configured to provide a torque of about 60 Nm/Kg, with the downside that the known Harmonic gears are not highly backdrivable.
  • the whole device, including the actuator weights from about 8Kg to about 15 Kg.
  • the actuator alone weights from about 600 gr to about 800 gr.
  • the actuator alone weights from about 500 gr to about 900 gr.
  • the actuator is used in an exoskeleton device configured to assist a user in walking, standing up and/or sitting down.
  • the actuator is configured to establish an ideal torque, velocity and range of motion (ROM) necessary to power these use cases.
  • the actuator has a lower reduction ratio, when compared to known actuators.
  • the actuator is configured to provide high torque together with high bandwidths while also being lightweight.
  • the actuator is configured to provide high backdrivability, when compared to known actuators, meaning, the actuator is configured to be manually moved from the output effortlessly.
  • a potential advantage of having a high backdrivability is that it potentially improves the implementation of force controls; for example, in this case, the reduction system is as transparent as possible to allow the simplification that the output torque is almost perfectly proportional to the input torque and avoid using a torque sensor.
  • an aspect of some embodiments of the invention relates to an actuator that provides high torque, comprises high backdrivability, is characterized by a low mass and it is potentially cheaper, when compared with known actuators.
  • the actuator provides a maximum output torque of about 64 Nm.
  • the actuator provides a maximum output torque of from about 50 Nm to about 80 Nm, optionally, from about 40 Nm to about 100 Nm.
  • the actuator provides a maximum output angular velocity of from about 33 min -1 to about 100 min -1 .
  • the actuator comprises a peak output power of from about 100W to about 750 W.
  • the high backdrivability is allowed due to a provision of a high torque-motor combined with a low-reduction-ratio gearbox, which comprises a high efficiency transmission mechanism of from about 90% to about 98%.
  • the high torque-motors are brushless motors with a high number of pole pairs and a high ratio diameter vs thickness.
  • the actuator is characterized by a low reduction ratio, which allows reducing the effect of inertial losses on the actuator, thus obtaining a high efficient system.
  • the actuator is characterized by an efficient reduction mechanism.
  • the weight and size reduction and relocation are achieved due to the use of a coaxial input-out layout.
  • an aspect of some embodiments of the invention relates to a backdrivable coaxial actuator, optionally for an exoskeleton, which is a quasi-direct drive actuator comprising a two-stage transmission, configured to provide a reduction ratio above 10.
  • the actuator comprises a high torque-motor coupled with a two-stage timing belt transmission, resulting in an energy-efficient actuator with high backdrivability, that offers high torques and speeds while keeping the system light and compact.
  • the backdrivability of the actuator facilitates the implementation of the most advanced control strategies without using expensive sensors.
  • the actuator is highly compact in relation to the maximum output torque, speed and backdrivability that it provides.
  • the coaxial actuator is provided by having the electric motor inside the output pulley/gear, which enables a denser/compacted package. In some embodiments, additionally, this enables the use of a two-stage timing belt transmission in a 4-actuated joint exoskeleton albeit space constraints.
  • An aspect of some embodiments of the invention relates to an actuator comprising a motor configured to provide a high torque output, comprises components that allow to provide medium to high reduction ratios that also allow to have a compact actuator.
  • the ratios are more than 10 and less than 50, for example between 12 and 36.
  • the actuator uses a two-stage transmission system.
  • two-stage transmission actuators are organized in a serial-linear layout, as shown for example in Figure 1a .
  • the input pulley 102 is connected to a mid pulley 106 by means of a first belt 104
  • the mid pulley 106 is connected to an output pulley 110 by means of a second belt 108.
  • the input pulley 102, the mid pulley 106 and the output pulley 110 are spatially arranged one after the other, as shown for example in Figure 1a .
  • the actuator comprises a compacted coaxial layout, as shown for example in Figure 1b .
  • the actuator of comprises an input pulley 102 that is connected to a mid pulley 106 by means of a first belt 104, and the mid pulley 106 is connected to an output pulley 110 by means of a second belt 108.
  • the parts of the actuator are not spatially arranged one after the other.
  • the input pulley 102 driven by the electric motor is positioned inside the area of the output pulley 110, thereby generating a coaxial layout.
  • a coaxial layout enables reducing the length of the actuator from about 20% to about 30%, optionally from about 15% to about 40%, optionally from about 10% to about 50%, for example 30%, 35%, 45%, when compared with a serial-linear layout.
  • the serial-linear actuator shown in Figure 1a comprises an estimated length of about 315mm
  • the compacted actuator as shown in Figure 1b comprises an estimated length of about 220mm.
  • a potential advantage of providing a compacted footprint for the actuator is that, in an exoskeleton, it potentially enables assembling both actuators between the knee and the hip joints (in the thigh body segment) even for the shortest configuration (see below).
  • the actuator uses a 2-stage timing belt transmission system designed in order to get the desired reduction ratio.
  • the reduction ratio of the actuator is tuned, for example, by changing the number of teeth of the pulleys.
  • the actuator is configured to allow reduction ratios from about 10 to about 20.
  • a first stage reduction is achieved between the input pulley 102 and the mid pulley 106, for example a reduction of 1:4.20 ratio; and a second stage of reduction is achieved between the mid pulley 106 and the output pulley 110, for example a reduction of 1:4.28 ratio.
  • the ratios of the actuator are from about 1:10 to about 1:20, optionally from about 1:8 to about 1:30, optionally from about 1:5 to about 1:40, for example, 1:14, 1:16. 1:18, 1:20.
  • the input pulley is actuated by a motor 302.
  • the motor 302 is a high torque-motor.
  • the high torque-motor is a large diameter flat brushless motor with a high number of poles and a very high Kt (torque-current constant).
  • Figure 3b shows the torque-motor 302.
  • the motor comprises one or more of the following characteristics: a high peak torque (Nm), a small weight (gr), a small height (mm) and/or a large diameter (mm).
  • the motor comprises a peak torque of about 6 Nm, a weight of about 366 gr, a height of about 18.6 mm and/or a diameter of about 86.8 mm.
  • the motor comprises a ring with permanent magnets and an iron core with the stator coils.
  • the motor does not comprise a frame.
  • a potential advantage of using a frameless motor is that it potentially allows design freedom and additionally saves weight and space in the overall device.
  • an exemplary motor used in the system is a T-motor Frameless U10 Kv25 motor, optionally with a RMB20 Rotary Magnetic Encoder Module.
  • exemplary technical characteristics of the motor include one or more of: a maximum current of about 9 A, optionally having a maximum current from about 8 A to about 15 A, optionally having a maximum current from about 5 A to about 30 A, optionally having a maximum current from about 3 A to about 50 A; a nominal torque of about 1.6 Nm, optionally having a nominal torque from about 1.4 Nm to about 2 Nm, optionally having a nominal torque from about 1 Nm to about 3 Nm, optionally having a nominal torque from about 0.5 Nm to about 6 Nm; a maximum torque of about 4.5 Nm, optionally having a maximum torque from about 4 Nm to about 6 Nm, optionally having a maximum torque from about 3 Nm to about 8 Nm, optionally having a maximum torque from about 2 Nm to about 12 Nm; a maximum speed of
  • the motor receives energy and commands from a circuitry, which controls the actions of the motor, and therefore of the actuator. In some embodiments, the motor receives modulated energy which dictates the actions of the motor, and therefore of the actuator.
  • the belts 104/108 are High Torque Drive (HTD) timing belts. In some embodiments, the belts 104/108 are High Power (HP) belts. In some embodiments, HP belts are used due to their low permanent and elastic stretch of the cord, friction and abrasion resistant fabric with high shear strength, and good resistance and smooth operation, low and medium shock load.
  • HTD High Torque Drive
  • HP High Power
  • HP belts are used due to their low permanent and elastic stretch of the cord, friction and abrasion resistant fabric with high shear strength, and good resistance and smooth operation, low and medium shock load.
  • FIGs 4a, 4b and 4c showing schematic representations of the actuators incorporated within an exoskeleton, according to some embodiments of the invention.
  • one or more actuators are used in an exoskeleton.
  • due to the compact footprint provided by the coaxial actuator it is possible to assemble two actuators between the knee and the hip even for the shortest configuration, as shown for example in Figure 4a , showing one leg part of an exoskeleton, as shown for example in Figure 4b , showing the one leg part of an exoskeleton showing the internal mechanism and the two actuators, and as shown in Figure 4c , showing an exploded view of the case of the exoskeleton and the internal mechanism of the exoskeleton.
  • parts of the exoskeleton are made of metals, for example, aluminum, titanium, etc.
  • parts of the exoskeleton are made of plastic and/or polymers, for example reinforced plastics.
  • knee actuator will be used to describe the actuator located close to the knee joint
  • hip actuator will be used to describe the actuator close to the hip joint.
  • the knee actuator and the hip actuator are identical and/or comprise the same parts. In some embodiments, the knee actuator and the hip actuator are different and/or do not comprise the same parts.
  • Figure 5a showing a schematic section view representation of a knee actuator of an exemplary exoskeleton, according to some embodiments of the invention.
  • Figure 5a shows the frameless torque-motor 302 comprising a motor stator 502 and a motor rotor 504. It is also shown the input pulley 102, the mid pulley 106 and the output pulley 110.
  • the exoskeleton comprises a servo drive 506, responsible for transforming the direct current (DC) of the power supply into the right coil excitation to move the motor at the desired torque or speed.
  • this servo drive can work in two modes: position and torque control.
  • the exoskeleton comprises one or more encoders 508a-b, (two are shown in Figure 5a see also Figure 5c ), which are a type of rotary sensor, which comprise a non-contact and frictionless design that minimizes mechanical wear, weight and volume. Not to mention the high angular resolution that guarantees excellent performance.
  • exemplary encoders can be RMB20 encoders from RLS ® .
  • Figure 5a it is schematically shown exemplary locations where the encoders 508a-b can be placed in the actuator, for example, one at the input rotor 508a and one at the output rotor 508b.
  • this dual-encoder design potentially provides precise real-time information of the input and output rotor position enabling a deep monitoring of the reduction system.
  • the knee actuator of the exoskeleton comprises a brake 510 (see also Figure 5d ).
  • the actuator integrates an electromagnetic brake 510 (as shown for example in Figure 5d ) and an output encoder 508b (as shown for example in Figure 5c ).
  • the electromagnetic brake 510 is used for safety purposes, being activated in the event of power loss, thus locking the joint to support the user in an upright position during the power loss.
  • the electromagnetic brake 510 is used only in the knee joints of the exoskeleton, thus locking the knee joints in the event of power loss, and therefore preventing the user from falling to the ground.
  • the hip joints do not comprise an electromagnetic brake 510, and therefore the hip joints are free (not locked) in the event of power loss (similar to typical passive leg braces).
  • the brake 510 boosts the efficiency of the exoskeleton since the actuator is configured to use the brake to lock the joint while the user is standing upright and not spend energy with the motors for that purpose while standing up (one of the situations where the users spend most of the time).
  • Figure 5d showing a schematic representation of an exemplary brake used in an actuator of an exoskeleton system, according to some embodiments of the invention.
  • the safety magnetic brake 510 blocks the joint in case of a power failure.
  • a potential advantage of having a magnetic brake is that it can potentially prevent any injury to the wearer in case of power failure and/or discontinuation.
  • the brake 510 is placed coaxially with respect to the motor and is coupled to the input stage of the actuator in order to take advantage of the reduction mechanism to amplify the braking force.
  • the brake could be either spring-actuated or magnetically actuated.
  • the actuator comprises a dedicated mechanism, which allows knowing the position of the output at all times while avoiding the need of two complex encoders.
  • the dedicated mechanism is a newly developed optical encoder for the output, as shown for example in Figure 5c .
  • the information given by the encoder 508b together with the information given by a single-turn absolute encoder 508a in the electric motor provides an exact position of the output without the need of a homing procedure.
  • the output encoder 508b and the output encoder gauge 512 are shown.
  • Figure 5b showing a schematic section view representation of a hip actuator of an exemplary exoskeleton, according to some embodiments of the invention.
  • Figure 5b shows the high torque-motor 302 comprising a motor stator 502 and a motor rotor 504. It is also shown the input pulley 102 , the mid pulley 106 and the output pulley 110 .
  • the actuator comprises a mechanism that allows the user to tension the belt.
  • the mechanism is an eccentric belt tensioner that allows tuning the belt initial tension with minimum space.
  • the tensioner consists of a ball bearing element 602 that rotates eccentrically around a bolt 604 and can be fixed in three different positions 606/608/610 by inserting a pin inside the desired hole, as schematically shown in Figure 6a .
  • the number provided in Figure 6a are exemplary numbers. Other dimensions of the ball bearing element are also possible.
  • Figures 6b, 6c and 6d schematically show how the belt is tensioned after each rotation of the ball bearing element, for example, an exemplary nominal length of a timing belt is about 425mm
  • the ball bearing element 602 in Figure 6b , the ball bearing element 602 is fixed in a first position 606 - low tension, bringing the belt to a length of about 425.09mm
  • the ball bearing element 602 in Figure 6c , the ball bearing element 602 is fixed in a second position 608 - medium tension, bringing the belt to a length of about 425.43mm
  • the ball bearing element 602 is fixed in a third position 610 - high tension, bringing the belt to a length of about 426.01mm.
  • the length of the thigh segment of the exoskeleton can be modified according to the needs of the user.
  • a thigh segment having a minimum size L which is suitable for shorter people.
  • a thigh segment that has been extended a length X bringing the total length of the thigh segment to a length of L+X, which is suitable for taller people.
  • the actuator comprises circuitry configured to control the activity of the actuator.
  • external circuitry for example incorporated in an exoskeleton, is connected to the actuator and is configured to control the actions of the actuator.
  • the efficiency of a motor is usually considered as the relation between the output mechanical power (T ⁇ ⁇ ) and the input electrical power (V ⁇ I).
  • the efficiency has a different value for each working condition (specific velocity and torque) and can range from 0 (when the output speed is 0) to a maximum value (which is usually specified as "the efficiency of the actuator").
  • the backdrivability is considered as the mechanical efficiency of an actuator between output axis and electric motor. Additionally, backdrivability is known as the easiness of moving an actuator from its output rotor. In other words, the torque required to move the output rotor. It should be noted the difference between both concepts.
  • Some motors can be efficient but not backdrivable, for example, a worm gear 1:5 is 95% efficient and 0% backdrivable.
  • the actuator of the invention comprises a low backdriving torque (meaning comprising high backdrivability).
  • a potential advantage of having an actuator comprising high backdrivability is that it potentially allows implementing control technics, which would be extremely difficult to implement with conventional motors, at least not without adding extra sensors.
  • Backdriving torque Cogging torque ⁇ Reduction ratio + Bearing Losses Timming belt efficiency
  • an exemplary reduction ratio of the system is of 1:17.96 (just as an example for the calculations), which provides a theoretical backdriving torque of about 1.7 Nm.
  • the contribution of each element without including the inertial contribution to backdriability is as shown, for example, in the graph as shown in Figure 8a .
  • the theoretical calculations match the experimental tests performed, which show a backdriving torque from about 1.7 Nm to about 1.98 Nm, using the exemplary reduction ratio of 1:17.96.
  • the backdriving torque is from about 1.2 Nm to about 2.0 Nm, optionally from about 0.5 Nm to about 2.5 Nm.
  • the nominal torque is from about 20 Nm to about 40 Nm, optionally from about 10 Nm to about 100 Nm.
  • the actuator in order to provide the system with higher backdrivability capabilities, the actuator comprises a lower reduction ratio in relation to parallel systems which are configured to provide similar output torques.
  • the motor of the system in order to compensate for the relative lower reduction ratio, the motor of the system is configured to compensate by delivering higher torques.
  • delivering higher torques means higher currents and/or higher phase resistance.
  • Joule Losses for example, in the form of heat
  • the graph shown in Figure 8b shows this trade-off, where it can be seen that an actuator according to some embodiemnts of the present invention consumes between 2.5 and 5 times more power in relation to other actuators at the same torque (36 Nm).
  • an exemplary exoskeleton may comprise a belt or a hip holder 906 and a back element 908 , optionally comprising a power source and main electronics.
  • the part of the exoskeleton comprising the actuators is a thigh element, in which the upper actuator, located near the hip, is configured to assist with the movements of the thigh itself from the hip, and the lower actuator, located near the knee, is configured to assist with the movements of the lower leg, by moving the lower leg element 910 , which is reversibly attached to the lower leg and optionally also to the foot.
  • elements that are actuated by the actuator are called actuated applied part, and are those that are attached to the body of the user.
  • the actuated applied part can be attached to one or more of a hip, a knee, a foot, an ankle, a wrist and an elbow.
  • the actuator is not driven by belts that connect between the pulleys, but directly driven by the gear teeth.
  • a motor 1002 provides speed and force to an input gear 1004 .
  • an upper part of the mid gear 1006 is meshed (in direct communication) with the first gear 1004.
  • a bottom part 1008 of the second gear 1006 is meshed (in direct communication) with an output gear 1010.
  • the beltless actuator is provided with lubricant material between the teeth of the gear to assist with the rotation of the gear and avoid damaging friction.
  • the actuator allows the placement of the actuators in any location of the human body (for example: near the human center of mass, or other proximal regions) and transmits the movement, for example, through Bowden cables to the desired joint (for example: distal region of the body).
  • the actuator comprises one or more motors 1102 (one is shown) connected to a system 1104, as explained above.
  • a simplification of the system is disclosed.
  • one or more cables 1106 exit from the reduction system, entering the hollow outer cable housing of Bowden cable system 1108.
  • the output pulley 1110 shown schematically, configured to provide the motion to the outside of the actuator to the relevant body part.
  • a potential advantage of utilizing a Bowden cable system is that it allows the use of the cable-driven actuator in an exoskeleton with a non-rigid mechanical structure made of textile parts (fabric harness), also known as soft exoskeleton or exosuit. This type of exoskeleton overcomes the movement restrictions of rigid exoskeleton systems, minimizing limitations in movement and reducing the weight of the device (weight-bearing relies on the user's skeletal structure alone), which is especially useful for people with mild motor disabilities.
  • the actuator comprising one or more motors 1102 is placed, for example, inside the back module 1112.
  • the actuation can be delivered by the output pulley 1110 to one or more extremities, for example, to the thigh 1114, to the knee 1116 and/or to the ankle 1118.
  • the one or more extremities are one or more of a shoulder, an elbow and a wrist.
  • FIG. 11c showing a schematic representation of an exemplary use of the exemplary cable-driven actuator in a soft exoskeleton, according to some embodiments of the invention.
  • the actuation mechanism as explained for Figures 11a and 11b , are used without using an output pulley 1110, by attaching the Bowden cable ends to the foot segment 1118 (one near the toe of the shoe and another one near the heel).
  • the release of the cable allows the ankle to move freely, while the tension of the cables blocks the movement of the ankle.
  • the actuator mechanism and motor 1102 are located at the back module 1112.
  • the cable is then redirected to the hip joint.
  • a potential advantage of redirecting the cable is that it potentially reduces the weight in the distal segment, which is potentially useful for people with little to no remaining motor function in their lower limbs.
  • the actuator can be used for the actuation of exoskeletons. It should be understood that the actuator can be used for other purposes, for example, for robotic machines, industrial robots, vehicles, toys, etc.
  • Figure 12a shows a schematic representation of an industrial robot or collaborative robot comprising the actuator according to some embodiments of the invention
  • Figure 12b shows a schematic representation of a four-legged robot comprising eight actuators according to some embodiments of the invention.
  • the exoskeleton comprises a battery configured to provide power to the whole system, for example, to the actuators, the electrical components, etc.
  • the battery is a rechargeable battery.
  • the backdrivable actuator is configured to utilize momentums from the movement of the patient wearing the exoskeleton in order to recharge the battery.
  • the motor is configured to provide speed and force to the pulleys in order to move an output element, which in this case, will move a body member of the patient wearing the exoskeleton.
  • the system is configured to detect when forces are inserted into the system, either by the momentum provided by the movement of the patient or by actively moving the output element, and utilize those forces to recharge the battery by converting those forces into energy.
  • recharging of the battery can be done by providing the exoskeleton with spring mechanisms in the foot that utilize the stepping actions performed by the user during walking in order to actuate the recharging mechanisms. Similar to what was explained above, the system utilizes forces directed to the system to transform them into energy for recharging the battery.
  • the actuator is an electrically powered actuator. In some embodiments, the actuator is pneumatically and/or hydraulically powered. In some embodiments, a potential advantage of using an electrically powered actuator is that electric batteries are quite compact compared to other power sources such as pneumatic compressors.
  • the size of the actuator is smaller than known actuators, for example, between about 10% to about 50% smaller in comparison to known actuators. Optionally between about 5% to about 60% smaller in comparison to known actuators. Optionally between about 1% to about 70% smaller in comparison to known actuators.
  • the actuator comprises an outer dimeter that is from about 50mm to about 200mm, optionally from about 40mm to about 250mm, optionally from about 30mm to about 275mm. In some embodiments, the actuator comprises an outer dimeter of less than 100mm. In some embodiments, a potential advantage of having a smaller actuator is that it provides a system that is less bulky to the user. In some embodiments, the actuator follows the shape of the human leg. In some embodiments, the actuator comprises a small form factor.
  • an exemplary actuator provides one or more of the following parameters:
  • the motor is "sensible” enough to sense forces coming from the output elements in the exoskeleton from the current drawn in the motor. For example, a user begins a movement to extend a leg. The movement of the leg will actuate the mechanisms of the actuator from the opposite direction, meaning, is not the motor that drives the movement of the actuator but rather the movement performed by the user that causes the movement of the actuator. In some embodiments, the motor can "sense” this movement and begin assisting the user by actuating the actuator in the same direction. In some embodiments, since the actuator comprises high backdrivability, this feedback mechanism using the current drawn by the motor is extremely useful in partially assisting the user to use the exoskeleton.
  • the actuator is configured to deliver a high torque in relation to the angular speed.
  • the actuator delivers a torque (Nm) / angular speed (RPMs) of from about 0.4Nm/RPM to about 1.6Nm/RPM of maximum torque / maximum.
  • the motor provides 60Nm and 83RPM, which is equivalent to 0.7 Nm/ RPM.
  • a requirement of the device comprising the actuator is to interact with the environment (for example, an exoskeleton with the patient and/or environment, an industrial robot with operators, the four-legged robot with the ground and obstacles and/or other machines), therefore the device is equipped with the backdrivable actuator enabled by a reversible motor.
  • the actuator comprises a reversibility torque vs. maximum torque ratio of less than 5%, ideally less than 2.5%, for example, the actuator comprises a reversibility torque of 1.55 Nm and provides a maximum of 60 Nm, which is equivalent to 2.5% reversibility torque / maximum torque ratio.
  • an exemplary main characteristic of the belt actuator is the combination of torque motor and a low reduction ratio transmission.
  • the torque motor used is a large diameter flat brushless motor with a high number of poles and a very high Kt (torque-current constant).
  • commercial High Torque Drive (HTD) timing belts are used in relation to the reduction system. More specifically, High Power (HP) belts are used due to their low permanent and elastic stretch of the cord, friction and abrasion resistant fabric with high shear strength, and good resistance and smooth operation, low and medium shock load.
  • HTD High Torque Drive
  • HP High Power
  • a two-stage timing belt system has been designed, as shown for example in Figures 1b and 2 .
  • Figures 5a and 5b show a section view of the knee and hip actuators. In some embodiments, both systems use exactly the same components except for the emergency brake that is optionally only placed in the knee actuator.
  • the system integrates a safety magnetic brake and an output encoder.
  • the normally-closed brake (it brakes when power is released) adds a safety layer to the device that in case of power loss will still hold the weight of the user. In addition, it boosts the efficiency of the exoskeleton as the motors will not spend any energy while standing up still (one of the situations where the users spend most of the time).
  • an exemplary brake is a 03.P1.310-400 brake from the manufacturer KEB. This brake of 11W and 24Vdc can deliver 2 Nm of constant braking torque in the input, which translates to 36 Nm of braking torque in the knee.
  • an optical encoder for the output has been included, as shown for example in Figure 5d .
  • the information given by this encoder together with the information given by a single-turn absolute encoder in the electrical motor, gives the exact position of the output without the need for a homing procedure.
  • the frameless motor as shown for example in Figure 13a , consists of a rotor (magnet ring) and a stator (soft iron core with copper coils) that are glued to a machined structure that transmits the torque generated by the motor.
  • a test bench as shown for example in Figure 13b , was built in order to obtain the motor constants and its thermal behavior: it is composed of a custom-made machined structure for the frameless motor, a torque sensor and a disk brake. Then, this test bench is connected to a driver controlled by a 32-bit Teensy ® USB-based microcontroller that reads and stores the data from the different sensors.
  • the drive configuration used in the tests includes the following parameters:
  • the encoder linearity test gives a measure of the coaxiality between the motor and the encoder. This is especially relevant because, depending on the misalignment, the effective output torque can be equal to or lower than expected. This test was performed in two conditions: half the nominal current and the nominal current. In both cases, two complete mechanical revolutions in opposite directions (in order to account for friction) were made. The test parameters were: Data sampling rate: 100Hz; Drive: Everest XCR; Steps: 12600 (increments of 0.03 mechanical degrees).
  • the torque constant determines the relationship between the quadrature current applied to the motor coils and the torque delivered by the actuator. This is sometimes an important parameter because it gives information on how much torque is being applied to the patient's leg.
  • the purpose of this test was to determine the relationship between the torque delivered by the motor and the time necessary to reach the maximum temperature of the stator coil. To do so, the motor was excited at different temperatures while the time to reach 100°C was measured, always starting at 24°C.
  • the test parameters were: Data sampling rate: 100 Hz; Drive: Everest XCR; Thermistor Model: NTCLE305E4103SB; ambient temperature: 24°C; Number of tested currents: 4 (3 A, 5 A, 10 A and 15 A). The results are reported in the graph shown in Figure 13e , where can be seen that the relationship follows an exponential curve.
  • an exemplary motor used by the actuator is an electric frameless motor, T-Motor U10 Kv50, together with a RMB20 Rotary Magnetic Encoder Module.
  • the 1 st stage comprised a Optibelt Omega HP 5MHP 425x9 belt, while the 2 nd stage comprised a Optibelt Omega HP 5MHP 475x25 belt.
  • Data acquisition rate 33Hz; Set-point updating rate: 1000Hz; Drive 1: Everest XCR; Drive 2: Everest XCR; Thermistor: NTCLE305E4103SB.
  • Quadrature current Velocity; Position; Temperature.
  • Figure 13h shows the main components of the test bench (the actuator and the resistance motor) together with the mechanical coupling composed of 1:2 timing belt.
  • the timing belt (8M 720x35) has been oversized to make sure it interferes as little as possible with the results.
  • Figure 13i shows charts showing the position, velocity and current profiles of 12 cycles (1 sitting down, 1 standing up and 10 steps).
  • the expected life of the actuator e.g., by knowing the maximum number of cycles that the actuator can withstand and the expected cycles per year, it is possible to determine the expected lifespan of the motor. Determining the average loads that the motor will suffer is almost impossible because each user will load the device differently based on their injury, weight, ability, etc. For this reason, the motor was loaded at its absolute maximum working conditions. This will lead to a shorter theoretical life expectancy than real.
  • Figure 13j shows the actuator uncovered after performing all the fatigue tests.
  • the first thing that can be seen is that there is some rubber debris all over the motor. This debris comes from the timing belts, and most of it was released in the last cycles of the test.
  • Figure 13k shows how the timing belt was affected by the teeth jump. Some of the teeth were damaged and were only partially attached to the belt cord. In addition, some of the belt cords were also damaged.
  • the motor synchronism is defined as the error between the input rotor angle and the human leg angle. This parameter shows how closely the human leg will follow the desired trajectory imposed on the motor. In some cases, the goal is to have the smallest possible error and, possibly more importantly, to have a constant error though all the actuator's expected lifespan.
  • the graph in Figure 13I shows the plot of the evolution of the input-output error during the whole fatigue test. It can be seen that the error does not increase over time, so the motor keeps its synchronization over time.
  • the motor current gives information about the actual torque that the system is delivering. By checking the current data, the severity of the test can be checked.
  • the graph in Figure 13m shows that the motor was doing the maximum possible effort during the fatigue test. It can be seen that the Root-Mean-Square current is equal to the nominal current and the peak current is always reached in each cycle.
  • the temperature data it is can be important to check if the fact of enclosing the frameless motor inside the actuator changes the thermal behavior of the system. To do so, the temperature of the stator coils was measured during the whole experiment.
  • the chart in Figure 13n shows that the temperature never reaches 100°C which is the maximum operating temperature specified by the manufacturer (T-Motor). In the chart, it can be seen that the temperature has a periodic fluctuation. This temperature variation is caused by the room temperature variation during day and night.
  • an exemplary method of providing an exoskeleton and/or transmitting power in an exoskeleton comprising an actuator comprising one or more of:
  • compositions, method or structure may include additional ingredients, steps and/or parts, but only if the additional ingredients, steps and/or parts do not materially alter the basic and novel characteristics of the claimed composition, method or structure.

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EP22382778.3A 2022-08-10 2022-08-10 Rückfahrbarer aktuator für exoskelett Pending EP4321772A1 (de)

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EP22382778.3A EP4321772A1 (de) 2022-08-10 2022-08-10 Rückfahrbarer aktuator für exoskelett
PCT/IB2023/055080 WO2024033712A1 (en) 2022-08-10 2023-05-17 Backdrivable actuator for exoskeleton

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EP22382778.3A EP4321772A1 (de) 2022-08-10 2022-08-10 Rückfahrbarer aktuator für exoskelett

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US20210338515A1 (en) 2017-02-08 2021-11-04 Parker-Hannifin Corporation Legged mobility exoskeleton device with enhanced actuator mechanism employing magnetic coupling
US20180296422A1 (en) * 2017-04-12 2018-10-18 Cleveland State University Actuating device for powered orthosis
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WO2021030086A1 (en) * 2019-08-14 2021-02-18 Parker-Hannifin Corporation Two stage actuator for powered mobilitity assistance devices with electrical isolation

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